I'm sure that your batteries are a lot lighter than mine. I am using full cell 3300 racing packs that are custom matched. I wasn't worried so much about the extra weight because of the 120, I was worried about losing the plane to lack of juice.

The CG is way back on the plane, so it must take that much movement to make a change.

When you flew your plane did you slow it down and do slow shallow turns? Did it look like it lost altitude if you didn't give a lot of up elevator? On final during the last few feet when you flared, what angle do you think the plane was at?